Identification of novel proteins involved in Vibrio cholerae motility

The causative agent of the infectious diarrheal disease cholera is the bacterium Vibrio cholerae. This bacterium naturally inhabits an aquatic environment and is highly motile by the action of a single polar sheathed flagellum. It has previously been shown that the loss of motility reduces the infectivity of V. cholerae, demonstrating that motility is an important factor required for the bacterium to initiate disease. My studies have focused on the characterization of novel proteins involved in motility. More specifically, we have identified three proteins that are important for stability of the flagellum; FlgO (VC2207), FlgP (VC2206) and FlgT (VC2208). We have determined that flagellar stability is important for proper motility. Moreover, we have established that proper motility is required for the initial attachment of V. cholerae to the intestine.;The flgO and flgP mutants produce fragile flagella that are readily broken by the shear forces that accompany motility. FlgO and FlgP localize to the outer membrane of the cell and may play a role in stabilizing the membrane and/or sheath of the flagellum. Additionally, the flgO and flgP mutants are defective in epithelial cell attachment and colonization. Through these studies, we have established that motility is absolutely required for initial attachment.;The flgT mutant is nonmotile and mostly aflagellate. Here we demonstrate that the flgT mutant is capable of assembling a flagellum, however the flagellum does not remain attached to the cell, but rather is released into the culture supernatant. We hypothesize that FlgT functions to anchor the flagellum to the cell. Moreover, the flgT mutant expresses traditional, nonflagellar virulence factors under nonpermissive conditions. However, our studies demonstrate that the flgT mutant is defective in attachment and colonization of the intestinal epithelium, further demonstrating the vital role of motility in pathogenesis. Together, these studies provide a better understanding of the importance of flagellar stability during the motile and sessile lifestyles of V. cholerae.